In recent years, full-backs have increased in importance in the Premier League, and left-backs are therefore amongst the division's key players.
Whereas in the past those on the left side of the back four would primarily be expected to defend, they are now often required to offer an attacking threat too - just look at Jurgen Klopp's Liverpool and Pep Guardiola's Manchester City.
Ashley Cole, Patrice Evra and Leighton Baines are just some of the names to have lit up the top flight with their performances from left-back.
But who is the best of the current crop? We have put together our top ten, ranked from worst to best, to try and give you an answer. But be warned, this is just our opinion and is not a definitive list!
All playing stats have been taken from Transfermarkt to ensure consistency.
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10. Pervis Estupinan
Marc Cucurella's switch to Chelsea was initially deemed to be a big loss for Brighton, especially given the Spaniard's performances last term. However, his replacement Estupinan, who, at £14.9m was signed for just a fraction of the initial £56m the Seagulls received for Cucurella, has been a revelation.
The Ecuador international impressed as Villarreal reached the Champions League semi-finals last season, and he has settled in fantastically at the Amex Stadium under new boss Roberto De Zerbi.
Unfortunately for Brighton, they are often at the mercy of the division's bigger clubs, with any top player immediately on the radar of the leading outfits. The south-coast-based team will be hoping to hold on to the 25-year-old for a while longer, though.
9. Tyrick Mitchell
Mitchell is now into his third full season at Crystal Palace and is his team's undisputed first choice at left-back.
He has developed particularly well as part of Patrick Vieira's new philosophy at Selhurst Park, which focuses on young players rather than a squad filled with older talent, and his displays have earned him two caps for England despite him playing in a position where there is plenty of competition.
Like Brighton with Estupinan, the Eagles may have to bat off interest from those above them in the food chain if they want to keep Mitchell at the club. Whether his future is at Palace or elsewhere, however, the 23-year-old surely has a promising career ahead of him.
8. Aaron Cresswell
Now in his ninth year at West Ham United, Cresswell is a Premier League veteran, and his consistency has made him one of the best in the division in his position.
The fans named him the club's Hammer of the Year following the 2014/15 season, his first in East London, and he has been one of the team's most reliable players ever since.
He has not been quite at his best this term, a drop which has coincided with the Hammers' general downturn in form, but David Moyes knows the 33-year-old is someone he can count on to help get the team out of the mess they are currently in.
7. Dan Burn
Considering his 6 ft 6 in frame, Burn was previously typecast as an aerially dominant centre-back who offered little in the way of technical ability.
However, first under Graham Potter at Brighton and now Eddie Howe at Newcastle United, the colossus has developed into an impressive left-back with a wide range of qualities and traits, which include composure in possession.
Howe has stated he believes Gareth Southgate should consider Burn for England and, on current form, it is hard to disagree with him. The Magpies may look to sign more of a specialist in that position in the future, but they could do a lot worse than the former Fulham and Wigan Athletic man.
6. Lucas Digne
Frenchman Digne has already turned out for Barcelona and Paris Saint-Germain in the past and has more than 40 caps for France, so the fact his last two clubs have been Everton and Aston Villa is somewhat of a surprise.
Villa, though, are ambitious, as they have shown with their heavy spending and, at his best, Digne is a force to be reckoned with. Even as the Toffees struggled towards the bottom of the table, the 29-year-old regularly contributed with assists, and he was even being pursued by Chelsea before he made the move to Villa Park.
Under Unai Emery, Villa will be eager to move up the Premier League table, and Digne has the ability to play a big role.
5. Ben Chilwell
A lot has been made of Reece James' importance to Chelsea during his spells on the sidelines this campaign, but Chilwell's unavailability has been just as crucial a blow.
It took a while for the England international to adapt to bigger expectations after his transfer from Leicester City to Stamford Bridge but, under Thomas Tuchel in particular, he became a key member of the starting XI and put in a great performance during the 2021 Champions League final as Chelsea beat Manchester City 1-0.
Injuries continue to curtail his impact but, if he can stay fit, he will be of great use to Potter moving forward.
4. Luke Shaw
Just when you begin to doubt Shaw, he shocks you and finds a run of performances that remind people just why Manchester United were so eager to sign him from Southampton when he was still a teenager.
He was regularly criticised by former United manager Jose Mourinho, yet worked his way back into the Red Devils' first XI and played a starring role as England reached the Euro 2020 final, even scoring the opener.
With a bit more consistency, he could be higher up this list. As it is, he will have to make do with fourth place, which is hardly an insult.
3. Joao Cancelo
It is a testament to Cancelo's ability that he would probably feature just a high, if not higher, in the list of the Premier League's best right-backs, too. However, given Guardiola also has Kyle Walker at his disposal, the Portugal international has often been deployed at left-back, with often devastating effect.
The former Juventus man has regularly contributed assists, and also chips in with the odd goal too. We all know Guardiola likes to rotate his side, yet Cancelo made 36 Premier League appearances last season.
At just 28 years of age, he has a good few years ahead of him, which is good news for City, but worrying for the rest of the division.
2. Oleksandr Zinchenko
Had Zinchenko been playing for almost any other team in the Premier League across the previous few years, we would have already been well aware of the extent of his talent However, he is only just receiving the recognition he deserves following his move to Arsenal.
He was used sparingly at the Etihad Stadium, but has quickly become a key player for Mikel Arteta's Gunners as they go in search of a first league title in 19 years.
His technical ability is flawless, while his leadership and experience of being involved in league-winning sides have been vital in a squad full of young players. Should Arsenal finish the season at the summit of English football, City may regret letting the Ukrainian depart.
1. Andy Robertson
Along with Trent Alexander-Arnold on the opposite flank, Robertson has helped revolutionise the role of the full-back in modern-day football - some feat when you consider he was signed for just £8m in 2017 from relegated Hull City.
In three of the four full Premier League seasons he has completed at Liverpool, he has registered at least ten assists. Add to that his pace, energy, tenacity and composure, and you have not only the best left-back in the Premier League, but perhaps in Europe.
As the Reds have floundered this season, Robertson has been one of the few players able to match his previous form. Although Virgil van Dijk and Alisson have been incredibly influential, the Scotland international may well be the best signing of the Klopp era, all things considered.
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